X-ray examination apparatus comprising a balanced supporting arm

Abstract

An X-ray examination apparatus for irradiating an object in different directions comprises a C-shaped support whereto there are secured an X-ray source, an X-ray detector and a counterweight. The counterweight is situated at the end of the arm which also carries the X-ray detector. The movement of the counterweight is such that for all positions of the X-ray detector the center of gravity of the support, the X-ray source, the X-ray detector and the counterweight is situated in the point of intersection of the axes of rotation (the isocenter). As a result, the support is continuously balanced and manual adjustment of the support is possible. Balancing is enhanced by a cast and hence light C-shaped support.

What is claimed is: 
     
       1. An X-ray examination apparatus including a column, a sleeve connected to the column and rotatable about a first horizontal axis, a C-shaped support movably secured to the sleeve for rotation about a second axis which intersects the first axis at right angles, said sleeve having a center of gravity offset from said first and second axes, an X-ray source secured to the support at a first support end and an X-ray detector secured to the support at a second support end, the X-ray detector being movable along a central ray of an X-ray beam emitted by the source, the combination therewith comprising: a counterweight movably secured to said second end;   means for coupling the counterweight to said detector such that a shift in the center of gravity of the X-ray detector upon displacement of the detector shifts the position of the counterweight; and   means for compensating for the shift in center of gravity of the detector including means for positioning the combined center of gravity of the support, X-ray source, X-ray detector and counterweight on the second axis over an adjustable range of distances of the detector relative to the source and for positioning the combined center of gravity of the sleeve, support, X-ray detector, X-ray source and counterweight on the first axis over said adjustable range of distances.   
     
     
       2. An X-ray examination apparatus as claimed in claim 1, characterized in that the C-shaped support is formed by a tubular profile provided with two running surfaces on an outer side, which profile comprises internal partitions, said profile, running surfaces and partitions being formed by a single casting having a wall thickness of between approximately 8 and 5 mm. 
     
     
       3. An X-ray examination apparatus as claimed in claim 1, characterized in that the X-ray detector comprises image intensifier tube. 
     
     
       4. An X-ray examination apparatus as claimed in claim 2, characterized in that the C-shaped support contains one of the alloys G-AlSi10MB(CU)WA and G-AlZn10Si8Mg. 
     
     
       5. An X-ray examination apparatus including a column, a sleeve connected to the column and rotatable about a first horizontal axis, a C-shaped support movably secured to the sleeve for rotation about a second axis which intersects the first axis at right angles, said sleeve having a center of gravity offset from said first and second axes, an X-ray source secured to the support at a first support end and an X-ray detector movably secured to the support at a second support end, the combination therewith comprising: a counterweight movably sectwed to said support;   means for coupling the counterweight to said detector such that a shift in the center of gravity of the X-ray detector upon displacement of the detector shifts the position of the counterweight, said counterweight being so constructed and positioned to compensate for the shift in center of gravity of the detector by maintnining the combined center of gravity of the support, X-ray source, X-ray detector and counterweight on the second axis over an adjustable range of distances of shift of positions of the detector relative to the source and by maintaining the combined center of gravity of the sleeve, support, X-ray detector, X-ray source and counterweight on the first axis over said adjustable range of distances.   
     
     
       6. The apparatus of claim S wherein said counterweight comprises a weight secured for translation in response to the displacement of said detector for maintaining the combined center of gravity of said weight and said detector in fixed position relative to the support regardless the displacement of said detector. 
     
     
       7. The apparatus of claim 6 wherein the combined center of gravity of the detector and weight are offset from said first axis to maintain the combined center of gravity of the siceve therewith on said first axis. .Iadd. 
     
     
       8.  An X-ray examination apparatus comprising: a column;   a sleeve connected to the column and rotatable about a first horizontal axis;   a C-shaped support movably secured to the sleeve for rotation as a unit about a second axis which perpendicularly intersects the first axis at a point of intersection, said support having first and second support ends;   an X-ray source secured to the support at the first support end;   An X-ray detector movably secured to the support at the second support along a central ray path directed between said detector and said source;   a counterweight movably secured to said support; and   coupling means between said X-ray detector and said counterweight for linking movement of said X-ray detector to movement of said counterweight such that over said adjustable range of positions of said X-ray detector along said central ray path, a shift in center of gravity of the detector is substantially compensated for by a shift in center of gravity of the counterweight in order to maintain a combined center of gravity of the support, X-ray source, X-ray detector, and counterweight on the second axis and to maintain a combined center of gravity of the sleeve, support, X-ray source, X-ray detector and counterweight on the first axis at a point spaced from said point of intersection. .Iaddend. .Iadd.9. An apparatus as claimed in claim 8, wherein said central ray path perpendicularly intersects said second axis at said point of intersection. .Iaddend. .Iadd.10. An apparatus as claimed in claim 9, wherein said counterweight is movably secured to said support at said second end. .Iaddend.